A device is known, which, during an audio communication service, can pick up audio packets passing through a network (for example, an IP (Internet Protocol) network, an NGN (Next Generation Network), the Internet, a mobile network, or the like), analyze audio quality, and detect deterioration in the audio quality. For example, by performing a header analysis of a UDP header or an RTP header, or an RTCP analysis or the like, it is possible to detect packet loss rate, round trip delay or one way delay, jitter, and the like. Furthermore, in a case where at least one of these exceeds a predetermined threshold, it is possible to determine deterioration of the audio quality, and to output an alarm or the like. An analysis result thereof or deterioration in audio quality is notified to an upper level monitoring device, and it is also possible to output and display this in a monitoring terminal, as it is, or after processing and editing.
Patent Document 1 discloses an example of the abovementioned audio quality analyzing device. According to Patent Document 1, use is made of a communication terminal provided with: a function 11c that assigns a time stamp of time-of-receipt to an audio/image packet received from a communication party and collects the time stamps, a function 11h that collects self-performance data, functions 11e, 11f, and 11g that compute information of transmission delay, packet loss rate, and fluctuations, arising from quality deterioration, based on information of sequence number and time stamp of collected audio/image packets and information of time stamp at time of transmission and sequence number from the communication party, a function 11i that determines whether or not these computed quality deterioration causes and information of the collected performance data exceed a threshold, and a function 11j that gives notification in a monitor that there is a possibility of the occurrence of quality deterioration in a case where the threshold is exceeded according to the determination, so as to enable advance notification of quality deterioration of multimedia communication to be given with high accuracy to a user.
Furthermore, Patent Document 2 discloses a configuration of an audio quality adjustment device for an IP network system provided with a plurality of VoIP gateway devices that perform relaying for packet forwarding with respect to IP (Internet Protocol) and transmission of audio signals in an existing public network, the configuration being provided with an evaluation means that instantaneously evaluates call audio quality for respective lines during a call via a transmission path by way of an IP network, based on information regarding VoIP packets reaching the VoIP gateway devices via the IP network, and an adjustment means that adjusts processing in which a VoIP gateway that is a source of a VoIP packet transmits to the IP network in accordance with the respective lines during the call.
Furthermore, Patent Document 3 discloses a communication device provided with a function to curtail deterioration of audio quality as much as possible, by embedding detection information of errors in ups of fixed length cells into which audio packets are packed when multiplexing packeted audio, extracting audio packets on a receiving side and measuring an error state of a communication path from the embedded error detection information, notifying transmission error excess to a transmission side in a case of exceeding a pre-set error generation condition, switching an audio encoding method to an encoding method with a strong audio quality characteristic with respect to encoding error in a transmission side communication device that receives this transmission error excess notification, and also controlling a multiplexing method.
Patent Document 4 discloses a configuration having a buffer that absorbs fluctuations in a packet switching network in a media stream relay device that relays between a circuit switching network and a packet switching network, wherein packet congestion and loss can be reduced.
Patent Document 5 discloses an audio quality monitoring method of sending a test audio signal to an IP network from a media gateway in a case where a test is necessary during system operation, picking up an audio signal that has returned via the network, obtaining the difference from the test audio signal, and performing monitoring of audio quality according to the extent of the difference. Furthermore, Patent Document 5 describes cutting an echo component by an echo canceller, with respect to a test audio signal including an echo component, and performing performance monitoring of the echo canceller by monitoring operation of the echo canceller using the audio signal after cutting.
Patent Document 6 discloses a configuration provided with a function of measuring echo amount, in a terminal connected to a packet network. An echo measuring method disclosed in Patent Document 6, is, specifically, an analog acoustic method of measuring echo amount by measuring audio loopback amount in respective parts of a VoP telephone, such as a handset (refer to paragraphs 0071 to 0073 in Patent Document 6.)
Patent Document 7 discloses a hybrid telephone system having an audio quality management function. A hybrid PBX described in the document has a test signal transmission function and a test result analysis function, and based on an analytic result thereof, optimizes the setting of each type of parameter with respect to audio quality in a call path with respect to an echo canceller.
[Patent Document 1]
    Japanese Patent Kokai Publication No. JP-P2004-289748A[Patent Document 2]    Japanese Patent Kokai Publication No. JP-P2005-57331A[Patent Document 3]    Japanese Patent Kokai Publication No. JP-P2003-87321A[Patent Document 4]    Japanese Patent Kokai Publication No. JP-P2007-288342A[Patent Document 5]    Japanese Patent Kokai Publication No. JP-P2004-328345A[Patent Document 6]    Japanese Patent Kokai Publication No. JP-P2003-244235A[Patent Document 7]    Japanese Patent Kokai Publication No. JP-P2005-176071A